1. Field of the Invention
The present invention relates to a radio selective calling receiver and, more particularly, to an individual radio selective calling receiver for selectively receiving a message transmitted by radio and having an identification number assigned thereto to be selectively called, and displaying the message.
2. Description of the Prior Art
Different identification numbers (to be referred to as ID numbers hereinafter), which are addresses used for selective calling, and corresponding telephone numbers are uniquely assigned to conventional individual radio selective calling receivers by a radio selective calling system manager. When a caller is to call a given individual radio selective calling receiver (user) to transmit a message thereto, the caller originates a call to the radio selective calling system to call at the corresponding telephone number as the destination, thus transmitting the message. The radio selective calling system adds an ID number corresponding to this telephone number to the message to generate a radio selective call signal, and transmits it as a radio signal through a radio base station. When each individual radio selective calling receiver receives the radio selective call signal and detects that an ID number identical to the stored self-ID number is contained in the received signal, the receiver recognizes that it is called, and receives and displays the succeeding message. In addition, the receiver notifies the user of the reception of the call by using a buzzer or the like.
Since the above conventional individual radio selective calling receivers respectively have different ID numbers, a calling operation must be performed a plurality of numbers of times to call the users of a plurality of individual radio selective calling receivers. In addition, even if a caller carries an individual radio selective calling receiver, since he/she cannot receive the message that he/she has transmitted, he/she cannot check whether the message has been accurately transmitted to the callees.
In order to solve this problem, as a scheme of simultaneously calling a plurality of individual radio selective calling receivers, a scheme has been proposed (Japanese Unexamined Patent Publication No. 4-329035), in which individual ID numbers are respectively assigned to a plurality of individual radio selective calling receivers held by a subscriber's family, in addition to a common telephone number, thereby allowing the users to arbitrarily select individual calling/simultaneous calling. According to this scheme, simultaneous calling is allowed only among a plurality of individual radio selective calling receivers held by the same subscriber, i.e., receivers to which the same telephone number is assigned. Furthermore, when simultaneous calling is performed, all these receivers are called, but an arbitrary combination of receivers cannot be called. This scheme cannot be applied to a radio selective calling system in which the ID numbers in selective call signals are converted in one-to-one correspondence with telephone numbers. Another simultaneous calling scheme has been proposed (Japanese Unexamined Patent Publication No. 59-15341), in which a common telephone number for simultaneous calling is assigned to a plurality of individual radio selective calling receivers, in addition to telephone numbers for individual calling. According to this scheme, however, a combination of receivers for which simultaneous calling is to be performed must be informed to the radio selective calling system manager in advance, and it is difficult to change the combination frequently. In addition, a caller must remember a common telephone number for simultaneous calling as well as an individual radio calling telephone number.